I wouldn't call Construct's level editor bad or inferior to GM's - even for tileset-based stuff. You just need to be wise about how to use your tileset - a combination of tiled background objects and sprites with sprite index works wonders for level creation.
The initial set-up time might be a bit longer, but once you have established the base, building things becomes quite fast - if you need something, it's very quick to just select one or multiple objects already existing in the level and ctrl+drag a copy of it in the new place. Maybe change one tile here and there, and tweak the width/height of some tiled backgrounds using the snap resizing to grid -function as help.
Take this tileset and starry sky here for example:
<img src="http://planar-studios.com/bin/tileset.png"><img src="http://planar-studios.com/bin/bgstars.png">
In relatively short time I came up with this:
It takes use of all the stuff I mentioned earlier, plus filters, layers and rotation for ease of work. Looks pretty slick, huh? It's very easy to expand as well when you already have stuff laying around in the layout - just ctrl+drag a copy of one or multiple things and do some little tweaking. I'd say it's quite a lot faster than selecting tiles from tileset every time when you want to add a different tile.
Here's the cap too: